This invention relates to novel cellulose ethers and detergent compositions containing the cellulose ethers as a soil release agent. More particularly, this invention relates to cellulose ethers having a low molecular weight and a high degree of methyl substitution. Detergent compositions containing the cellulose ethers give soil release properties to washed fabrics thereby rendering the fabrics easier to clean in subsequent washings.
Cellulose ethers are a well known class of materials. They are generally derived from vegetable tissues and fibers, including especially cotton and wood. The molecular weight of such cellulose ethers vary from about 19,000 to about 185,000. The molecular weight of the cellulose materials can be reduced by various means including aqueous acid hydrolysis, oxidative depolymerization, and by reaction with gaseous hydrogen chloride. For example, see U.S. Pat. No. 3,391,135, July 2, 1986, Ouno et al, and British Pat. No. 1,139,637, published Jan. 8, 1969. Changing the molecular weight of a cellulose ether necessarily affects its physical properties.
The hydroxyl groups of the anhydroglucose unit of cellulose can be reacted with various agents thereby replacing the hydrogen of the hydroxyl with the reacting agent. For example, various alkylating and hydroxyalkylating agents have been reacted with cellulose materials to produce alkyl cellulose ethers and hydroxyalkyl cellulose ethers. The degree of substitution may vary up to 3.0 since there are three available positions on each anhydroglucose unit. The kind of substitution and degree thereof also has an effect on the physical properties of the cellulose material.
Detergent compositions containing various soil release agents are known. In particular, various cellulose ethers have been used in detergent compositions for the soil release benefit they are able to impart to washed fabrics. For example, see U.S. Pat. No. 3,668,000; U.S. Pat. No. 2,994,665; U.S. Pat. No. 3,523,088; South African Patent Application No. 71,5149; and British Pat. No. 1,171,877. Copending commonly assigned Ser. No. 560,764, "Alkyl Sulfate Detergent Composition", Nicol et al., now U.S. Pat. 4,000,093 discloses the use of cellulose ethers including methyl cellulose ethers in detergent compositions.
While certain of the prior art cellulose ethers have been able to efficiently and effectively deposit upon fabrics and thus provide a soil release benefit, there are consequent negatives involved. It has been found that deposition of certain prior art cellulose ethers on fabrics causes a negative in particulate soil removal. More specifically, when such treated fabrics are subsequently stained with particulate soil, e.g. clay, and washed, the stains are more difficult to remove. It is believed the cellulose ether provides a bonding sight for the particulate soil, thus causing its removal to be more difficult.
It is an object of this invention to provide novel cellulose ethers suitable for use in detergent compositions.
It is another object of this invention to provide detergent compositions which impart soil release properties to fabrics without causing particulate soil removal negatives.
Still another object of this invention is to provide detergent compositions which impart oily soil release properties to fabrics without causing particulate soil removal negatives.
These and other objects of the invention will become apparent from the description to follow.
As used herein, all percentages and ratios are by weight unless otherwise specified.